1. Field of the Invention
This invention relates generally to electronic apparatus which utilize strain gauges installed in load cells, and more particularly, to electronic apparatus for processing of strain gauge signals to drive chart recorders and for a digital voltmeter calibrated to readout in pounds from applied muscle tension.
2. Description of the Prior Art
Load cells and associated electronic circuitry are routinely used to weigh everything from diamonds to meat to freight cars. Specialized load cells with its associated electronic circuitry have also been used in the past and are still presently being used for measurement of high static forces and torque. While load cell electronic systems have been incorporated into weighing systems designed for accurate weighing of humans, the relatively high cost of such systems has limited their adoption prior to the advent of reliable low-cost integrated circuits.
The user of the strength meter described in this disclosure applies muscle tension to an unyielding load cell unit which results in an isometric or static force measurement. This differs from a typical ergometer measurement which evaluates dynamic human effort in terms of energy. Thus, isometers involve measurement of a static force or weight without involving movement of the force or weight sensor whereas ergometers measure dynamic effort or energy which involves movement of the effort or energy sensor of the ergometer.
U.S. Pat. No. 3,995,492 issued Dec. 7, 1976 to Manfred E. Clynes describes a sound producing isometric exerciser. This is a dumb bell or dog bone shaped object, sized to fit conveniently in both hands and covered with plush fur pile or padded leatherette. By the user grasping the ends of the exerciser, the user is able to exert a compressive or tension force on a transducer coupled to a rigid link within the exerciser device. The transducer converts this applied force into a corresponding electrical value that is processed by a pulse generator and audio oscillators which are coupled to a loudspeaker housed within the structure, thereby producing a train of audible pulses whose repetition rate, tone and amplitude depend upon the applied force. Thus, the user receives a continuous sound which is maintained as long as the same level of force is applied. However, this sound can be varied by changing the applied force. By means of a "bleep" counter responsive to the audio output of the pulse generator, the user's performance is scored.
However, while this device described in U.S. Pat. No. 3,995,492 appears to be suited for indicating when an arbitrary but unknown muscle force level has been reached, as in a series of isometric exercises, it is not suitable for measurement of absolute or ultimate muscle strength in units such as pounds and provide a clear readout identifying the exact magnitude of the applied force.
U.S. Pat. No. 3,913,563 issued Oct. 21, 1975 to Newton E. Ball describes a transducer designed to function in a muscle contraction (primarily for pregnant women) monitor. Output of the transducer described in U.S. Pat. No. 3,913,563 is combined with other physiological measurements in a patient monitoring system.
Accordingly, none of the cited prior art discloses an apparatus which permits a user of the apparatus to obtain a read-out in units of force which can be used as a measurement of strength and growth of strength. Therefore, a need existed for such an apparatus to permit a user thereof to monitor strength capabilities.